/*
* This file is part of the DiffX library.
*
* For licensing information please see the file license.txt included in the release.
* A copy of this licence can also be found at
* http://www.opensource.org/licenses/artistic-license-2.0.php
*/
package com.topologi.diffx.sequence;
import java.util.Stack;
import com.topologi.diffx.event.CloseElementEvent;
import com.topologi.diffx.event.DiffXEvent;
import com.topologi.diffx.event.OpenElementEvent;
/**
* A utility class for event sequences.
*
* @author Christophe Lauret
* @version 3 April 2005
*
* @since 0.6
*/
public final class EventSequenceUtils {
/**
* Prevent creation of instances.
*/
private EventSequenceUtils() {
}
/**
* Indicates whether the sequence corresponds to well-formed XML.
*
* @param sequence The sequence.
*
* @return <code>true</code> if the sequence is "well-formed";
* <code>false</code> otherwise.
*/
public static boolean isWellFormed(EventSequence sequence) {
// TODO: if the sequence is null ??
if (sequence == null) return false;
Stack<DiffXEvent> open = new Stack<DiffXEvent>();
DiffXEvent e = null;
for (int i = 0; i < sequence.size(); i++) {
e = sequence.getEvent(i);
if (e instanceof OpenElementEvent) {
open.push(e);
} else if (e instanceof CloseElementEvent) {
if (open.empty()) return false;
OpenElementEvent o = (OpenElementEvent)open.peek();
String lastOpenElementName = o.getName();
String closeElementName = ((CloseElementEvent)e).getName();
if (!closeElementName.equals(lastOpenElementName)) return false;
}
}
return open.empty();
}
/**
* Returns the maximum depth of the sequence.
*
* <p>This method assumes that the sequence is well-formed, and counts
* the maximum number of open element events.
*
* @param sequence The sequence
*
* @return The maximum depth.
*/
public static int getMaxDepth(EventSequence sequence) {
int max = 0;
int depth = 0;
for (int i = 0; i < sequence.size(); i++) {
if (sequence.getEvent(i) instanceof OpenElementEvent) {
depth++;
} else if (sequence.getEvent(i) instanceof CloseElementEvent) {
depth--;
}
if (depth > max) {
max = depth;
}
}
return max;
}
/**
* Returns the maximum number of token inside an element tag.
*
* <p>This method assumes that the sequence is well-formed.
*
* @param sequence The sequence.
*
* @return The maximum number of tokens.
*/
public static int getMaxElementContent(EventSequence sequence) {
int max = 0;
int tmp = 0;
for (int i = 0; i < sequence.size(); i++) {
DiffXEvent e = sequence.getEvent(i);
if (e instanceof OpenElementEvent) {
tmp = 0;
} else if (e instanceof CloseElementEvent) {
if (tmp > max) {
max = tmp;
}
} else {
tmp++;
}
}
return max;
}
}